Facts on Residential Loops

Four Basic Geothermal Energy Sources

Closed-loop systems circulate a water-based solution through a "loop" of small-diameter, underground pipes. Closed-loop systems can be installed horizontally, vertically or in a pond. Open-loop systems use an existing water well. Regardless of whether the system is open or closed, heat is transferred to or from the home to provide year-round comfort, no matter what the outdoor temperature is.

Horizontal LoopsThese are often considered when adequate land surface is available. Pipes are placed in trenches that range in length from 100 to 400 feet.

Vertical LoopsThese are the ideal choice when available land surface is limited. Drilling equipment is used to bore small-diameter holes from 75 to 300 feet deep.

Pond (Lake) Loops These are very economical to install when a body of water is available, because excavation costs are virtually eliminated. Coils of pipe are simply placed on the bottom of the pond or lake.

Open loopsThese use groundwater as a direct energy source. In ideal conditions, an open-loop application can be the most economical type of geothermal system.